There has been a long demand for simple and rapid desktop manufacturing processes capable of decreasing the cost, time, and labor associated with micro- or nano-fluidic system fabrication in device prototyping and low volume production.
Due to the relative ease and speed of fabrication afforded by the soft lithography technique with polydimethylsiloxane (PDMS) elastomer, PDMS has been widely used in device prototyping of microfluidic applications. However, PDMS suffers from a number of disadvantages such as low stiffness, high gas permeability, high water absorption, and incompatibility with many common solvents used in biomolecular assays. More fundamentally, although within certain constraints a PDMS chip may be prototyped from design to final sealed device within several days, elastomer micromolding processes remain far from meeting the goals of true desktop manufacturing, with the microfabrication of templates needed for PDMS molding often requiring significant infrastructure, time, and labor.
Thermoplastic polymers are attractive materials for the fabrication of a variety of micro- or nano-systems, with applications including micro- or nano-optical components, microcantilever chemical sensors, micro- or nano-structured biomimetic surfaces, and micro- or nano-fluidic chips. Unlike elastomers such as PDMS, thermoplastic polymers offer a combination of excellent dimensional stability, good optical properties, low water absorption and gas permeability, low cost, and a range of bulk and surface properties. Thermoplastic micro- or nano-fabrication has been widely explored using conventional replication methods, for example, hot or colds embossing, injection molding, hot roller microprinting and thermoforming, as well as serial fabrication methods such as direct laser machining and micromilling. While these techniques provide advantages in some aspects, they all require significant infrastructure investment, time, and effort. Still more, all these conventional methods involve material removal or displacement through thermal or mechanical means. When device features are miniaturized to micro- or nano-scales, thermal or mechanical means of machining or patterning place a challenge on the mechanical properties of the structural materials for the device. It is generally difficult to control the drill bits or heating temperature so that features of micrometer or even nanometer scale are produced with high replicability and less deformation.
The orogenic fabrication methods disclosed in the current invention are simple and rapid desktop manufacturing processes capable of decreasing the cost, time, and labor associated with thermoplastic micro- or nanon-fluidic system fabrication. Based on the irreversible swelling of thermoplastic polymer upon exposure to a suitable solvent, one advantage of the current invention is that it can be carried out with or without lithography or micromolding. Another advantage of the current invention is that bonding of substrate can be achieved at room temperature and low pressure. The current invention provides a quick, economic and highly controllable means to achieve low volume production or prototyping of micro- or nano-fluidic device.